Microstructure of interpass rolled wire + arc additive manufacturing Ti-6Al-4V components

Mechanical property anisotropy is one of the issues that are limiting the industrial adoption of additive manufacturing (AM) Ti-6Al-4V components. To improve the deposits’ microstructure, the effect of high-pressure interpass rolling was evaluated, and a flat and a profiled roller were compared. The microstructure was changed from large columnar prior beta grains that traversed the component to equiaxed grains that were between 56 and 139 μm in size. The repetitive variation in Widmanstätten alpha lamellae size was retained; however, with rolling, the overall size was reduced. A “fundamental study” was used to gain insight into the microstructural changes that occurred due to the combination of deformation and deposition. High-pressure interpass rolling can overcome many of the shortcomings of AM, potentially aiding industrial implementation of the process.EPSRC, AirBu

Investigation of low current gas tungsten arc welding using split anode calorimetry

Most previous split anode calorimetry research has applied high weld currents which exhibit pseudo Gaussian distributions of arc current and power density. In this paper we investigate low current arcs and show that both the current and power distributions have minima in the centre – varying significantly from the expected Gaussian profile. This was postulated due to the formation of the arc with the copper anode and the tungsten cathode. Furthermore, a number of parameters were varied including the step size between measurements, anode thickness and anode surface condition as well as cathode type and tip geometry. The step size between measurements significantly influenced the distribution profile and the anode thickness needed to be above 7 mm to obtain consistent results

Pyrolysis-catalytic reforming/gasification of waste tires for production of carbon nanotubes and hydrogen

The production of high-value carbon nanotubes and hydrogen from the two-stage pyrolysis catalytic-steam reforming/gasification of waste tires have been investigated. The catalysts used were Co/Al₂ O₃ , Cu/Al₂ O₃ , Fe/Al₂ O₃ and Ni/Al₂ O₃ . The pyrolysis temperature and catalyst temperature were 600 °C and 800 °C, respectively. The fresh catalysts were analysed by temperature programmed reduction and X-ray diffraction. The product gases, including hydrogen were analysed by gas chromatography and the carbon nanotubes characterized by scanning and transmission electron microscopy and Raman spectrometry. The results showed that the Ni/Al₂ O₃ catalyst produced high quality multiwalled carbon nanotubes along with the highest H₂ yield of 18.14 mmol g⁻¹ tire, compared with the other catalysts, while the Co/Al₂ O₃ and Cu/Al₂ O₃ catalysts produced lower hydrogen yield, which is suggested to be associated with the formation of amorphous type carbons on the surface of the Co/Al₂ O₃ and Cu/Al₂ O₃ catalyst

High-pressure/high-temperature synthesis of transition metal oxide perovskites

Perovskite and related Ruddlesden-Popper type transition metal oxides synthesised at high pressures and temperatures during the last decade are reviewed. More than 60 such new materials have been reported since 1995. Important developments have included perovskites with complex cation orderings on A and B sites, multiferroic bismuth-based perovskites, and new manganites showing colossal magnetoresistance (CMR) and charge ordering properties

Conceptualizing Academic Library Use: Results of a Survey of Continuing Education Students in a Small Canadian Undergraduate University

This paper analyzes data from a survey of 4,084 continuing education students in a small Canadian undergraduate university to document and conceptualize patterns of library services use and factors influencing use. Factor analysis, multiple regression and analysis of variance are employed to examine the impact of three sets of explanatory variables on academic library use: student characteristics (e.g., age, sex and previous education); perceptions of problems limiting library use; (e.g., the adequacy of the collection, hours, and access to materials); and characteristics of the student's program of study (e.g., field of study, type of program, number of library-related assignments). The findings show that the most frequently used university library services, accounting for almost half of all use, were the study areas and the photocopy machines. The characteristics of the student's program of study including the extent to which library use was integrated into assignments and classroom discussion was found to be a strong predictor of use. The paper concludes that when conceptualizing and planning library services greater attention must be given to the broader learning environment of which the library is part and to the characteristics and needs of increasingly diverse student populations.L'auteur examine les résultats d'un sondage auquel ont participé 4 084 étudiants inscrits à des programmes d'éducation permanente dans une petite université canadienne offrant exclusivement des études de premier cycle. Ce sondage avait pour but de documenter les habitudes des étudiants sur le plan de leur utilisation des services fournis par la bibliothèque, en vue de conceptualiser cette utilisation et d'en déterminer les principaux facteurs. L'auteur a recours à l'analyse factorielle, à l'analyse par régression multiple et à l'analyse de la variance comme méthodes pour étudier les effets de trois ensembles de variables permettant d'expliquer l'utilisation de la bibliothèque universitaire, à savoir: caractéristiques des étudiants (p. ex., âge, sexe, et scolarité); perceptions des problèmes pouvant limiter l'utilisation de la bibliothèque (p. ex., suffisance de la collection, heures d'ouverture, accès aux documents); particularités du programme d'études suivi part l'étudiant (p. ex., domaine d'études, type de programme, nombre de travaux exigeant la fréquentation de la bibliothèque). Les résultats du sondage indiquent que les aires d'études et les photocopieurs figuraient parmi les services les plus utilisés à la bibliothèque, ce qui correspond à environ la moitié du temps d'utilisation de ceux-ci. Les particularités du programme d'études suivi par l'étudiant, y compris le nombre de travaux et de discussions en classe nécessitant la fréquentation de la bibliothèque, constituaient un important élément de prédiction relativement à l'utilisation. À titre do conclusion, l'auteur indique que, pour conceptualiser et planifier des services de bibliothèque, il faut accorder plus d'importance au milieu d'apprentissage global, duquel la bibliothèque fait notamment partie, ainsi qu'aux caractéristiques et aux besoins d'une population étudiante de plus en plus variée

The role of informal protected areas in maintaining biodiversity in the Western Ghats of India

Although it is widely believed that an important function of protected areas is to conserve species that are unable to survive elsewhere, there are very few empirical studies in which a comparison is made between biodiversity of protected areas and that of the cultivated landscape surrounding them. We examined the diversity of trees, birds, and macrofungi at 58 sites in three land-use types in a tree-covered landscape in Kodagu district in the Western Ghats of India. Ten forest reserve sites in the formal protected area, and 25 sacred groves and 23 coffee plantations in the neighboring cultivated landscape were sampled. A total of 215 tree, 86 bird, and 163 macrofungus species were recorded. The forest reserve had a large number of trees that were restricted in their distribution, and the sacred groves had a large number of macrofungi. We observed that deciduous trees and non-forest-dwelling birds increased, and evergreen trees and forest-dwelling birds decreased with increasing intensity of land management. We found that trees having non-timber uses and macrofungi useful to the local people, as well as those with medicinal properties, were abundant in sacred groves. We found no significant differences in the distribution of endemic and threatened birds across the three land-use types. Although endemic trees were more abundant in the forest reserve than in sacred groves, threatened trees were more abundant in sacred groves than in the forest reserve. We attribute the high diversity in sacred groves to the native tree cover in shade coffee plantations. We conclude that informal protected areas are as important as formal ones for biodiversity conservation in Kodagu. We recommend that a conservation strategy that recognizes informal protection traditions is essential for successful biodiversity conservation in regions where formal reserves are surrounded by a matrix of cultivated land

Context-Dependent Memory under Stressful Conditions: The Case of Skydiving

Two experiments examined the effect of differing levels of emotional arousal on learning and memory for words in matching and mismatching contexts. In Experiment 1, experienced skydivers learned words either in the air or on the ground and recalled them in the same context or in the other context. Experiment 2 replicated the stimuli and design of the first experiment except that participants were shown a skydiving video in lieu of skydiving. Recall was poor in air-learning conditions with actual skydiving, but when lists were learned on land, recall was higher in the matching context than in the mismatching context. In the skydiving video experiment, recall was higher in matching learn-recall contexts regardless of the situation in which learning occurred. We propose that under extremely emotionally arousing circumstances, environmental and/or mood cues are unlikely to become encoded or linked to newly acquired information and thus cannot serve as cues to retrieval. Results can be applied to understanding variations in context-dependent memory in occupations (e.g., police, military special operations, and Special Weapons and Tactics teams) in which the worker experiences considerable emotional stress while learning or recalling new information